In recent years, biopolymers represented by collagen and gelatin have been used in the field of regenerative medicine which has been energetically studied at home and abroad. For instance, it has been shown that ischemic disease lesions can be significantly improved by embedding a gelatin composition comprising a gelatin sponge (Patent Document 1) containing cell growth factors in such lesions on the legs or the chest and attaching such composition to defects on the skin surface.
Biopolymer sponges lack strength and promote bacterial growth, which are problematic. Therefore, it is necessary to reinforce or coat the above composition, depending on the diseases to which the composition is applied. For instance, in the case of skin ulcer treatment, a sponge containing growth factors is attached to the skin surface. As a result, the gelatin portion of the sponge is exposed to the exterior. In general, synthetic polymer supports are often used to reinforce or coat biopolymers.
Usually, synthetic polymers are less likely to adhere to biopolymers. Synthetic polymer cannot adhere to biopolymers by itself. For adhesion between synthetic polymers and biopolymers, adhesives are used. Alternatively, adhesion is achieved by physical suturing.
In general, most adhesives are poorly biocompatible. Therefore, when adhesives come into contact with biological tissues, inflammation or an allergic reaction might be induced. In addition, in the case of physical suturing, mechanical strains are concentrated on the suture, which might result in destruction of a composition at the suture site. Therefore, in the medical practice, a technique for attaching a medical composition to a synthetic polymer substrate with the use of a biopolymer, but not a toxic adhesive, has been awaited.    [Patent Document 1] JP Patent Publication (Kokai) No. 2005-213449 A